Rubber material

ABSTRACT

A rubber material which is a cured rubber having a hardness of from 30° as measured with an A-type rubber hardness tester to 15° as measured with an F-type rubber hardness tester and an impact resilience of not less than 50%. The material has excellent vibration-proof, sound-proof, shock-absorbing or cushioning properties and is useful as a material for vibration-proof, sound-proof, shock-absorbing and cushioning members.

BACKGROUND OF THE INVENTION

The present invention relates to a novel rubber material. Moreparticularly, it relates to a rubber material having a hardness of from30° as measured with an A-type rubber hardness tester to 15° as measuredwith an F-type rubber hardness tester and an impact resilience of notless than 50%, which material is especially useful as vibration-proof(or vibration-isolating, vibration-absorbing or vibration-damping)materials, sound-proof (or sound-isolating or sound-absorbing)materials, shock-absorbing materials or cushioning materials.

A variety of rubber materials have so far been used as vibration-proof,sound-proof, shock-absorbing or cushioning materials. However,conventional vibration-proof materials are poor in vibration-absorbingcharacteristics, especially in the superlow frequency range of about 5Hz to about 10 Hz. Therefore, when such rubber materials are used inmaking rubber sheets for record player turntable, vibration insulatorsfor record player, etc., outside vibrations cannot be excludedefficiently, hence high fidelity reproduction of source sound can hardlybe expected. Conventional sound-proof, shock-absorbing or cushioningrubber materials are also unsatisfactory.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide a novel rubbermaterial having excellent vibration-proof, sound-proof, shock-absorbingand cushioning properties.

This and other objects of the present invention will become apparentfrom the description hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view illustrating an embodiment ofthe vibration insulator wherein the rubber material of the presentinvention is used,

FIG. 2 is a plan view thereof,

FIG. 3 is a plan view of the reverse side and

FIG. 4 is an enlarged cross-sectional view taken along the line A--A inFIG. 2.

FIG. 5 is an enlarged partial perspective view of one array ofprojections.

FIG. 6 is a plan view illustrating another example of the mode ofarrangement of projections.

FIG. 7 is a vertical cross-sectional view of a vibration insulatorwherein the height of projections is varied depending on the array towhich the projections belong.

FIG. 8 is a vertical cross-sectional view of a vibration insulator, thebody of which has a laminated structure comprising a plurality of rubbermaterials different in physical properties.

FIG. 9 is a vertical cross-sectional view illustrating a vibrationinsulator, the body of which is cylindrical.

FIG. 10 is a developed view illustrating an example of the mode ofarrangement of projections provided on the side face of the cylindricalbody.

FIG. 11 is a vertical cross-sectional view of a vibration insulatorwhich can be attached to an other member to be supported by insertionand FIG. 12 is a plan view thereof.

FIG. 13 is a vertical cross-sectional view of a vibration insulatorusable as a cushion, for instance, employed at the mounting place for amotor in a record player, FIG. 14 is a plan view thereof and FIG. 15 isa vertical cross-sectional view illustrating the manner of attachment ofthe insulator shown in FIGS. 13 to 14.

FIG. 16 is a vertical cross-sectional view of another example of thevibration insulator wherein the rubber material of the present inventionis used and FIG. 17 is a plan view thereof.

FIG. 18 is a vertical cross-sectional view of the first vibration-proofmember of the insulator shown in FIGS. 16 to 17, FIG. 19 is a plan viewof the first vibration-proof member, FIG. 20 is a verticalcross-sectional view of the secnd vibration-proof member and FIG. 21 isa plan view of the second vibration-proof member.

FIG. 22 is a vertical cross-sectional view illustrating a modificationof the insulator shown in FIGS. 16 to 21.

FIG. 23 is a vertical cross-sectional view illustrating still anotherexample of the vibration insulator wherein the rubber material of thepresent invention is used and FIG. 24 is a plan view of the bottomthereof.

FIGS. 25 and 26 are vertical cross-sectional views respectivelyillustrating modifications of the insulator shown in FIGS. 23 to 24.

FIG. 27 is a perspective view of an example of the deadening memberwherein the rubber material of the present invention is used and FIG. 28is a cross-sectional view illustrating the state that the deadeningmember shown in FIG. 27 is attached to a turntable.

FIG. 29 and FIG. 30 are perspective views respectively illustratingother examples of the deadening member wherein the rubber material ofthe present invention is used.

FIG. 31 is a schematic representation of the destructive test apparatusused in examining rubber materials for possible influence upon thetester.

FIG. 32 and FIG. 33 are diagrams illustrating pressure curves for thetest piece from the rubber material of the present invention and thetest piece from a conventional ethylene-propylene-diene rubber,respectively.

FIG. 34 is a cross-sectional view illustrating the state of deformationof the tester after the test has been carried out employing the testpiece from the ethylene-propylene-diene rubber.

FIG. 35 is a plan view of an example of the bumper wherein the rubbermaterial of the present invention is used and FIG. 36 is an enlargedcross-sectional view taken along the line B--B in FIG. 35.

FIG. 37 is a cross-sectional view illustrating another example of thebumper.

FIG. 38 is a partial perspective view illustrating an example of thesealing member wherein the rubber material of the present invention isused and FIG. 39 is an enlarged cross-sectional view taken along theline C--C in FIG. 38.

FIG. 40 is a perspective view illustrating an example of the cushioningmember wherein the rubber material of the present invention is used.

FIG. 41 is a vertical cross-sectional view illustrating a cushioningmember having a laminated structure comprising a plurality of rubbermaterials different in physical properties.

FIG. 42 is a plan view of a ring member for use in a non-puncture tire,which membker is composed of the rubber material of the presentinvention and FIG. 43 is an enlarged cross-sectional view taken alongthe line D--D in FIG. 42.

FIG. 44 is a cross-sectional view of a non-puncture tire equipped withthe ring member.

FIG. 45, FIG. 46, FIG. 47 and FIG. 48 are cross-sectional viewsrespectively illustrating various modifications of the ring member.

FIG. 49 is a cross-sectional view illustrating an example of the solidtire wherein the rubber material of the present invention is used.

DETAILED DESCRIPTION

The present invention provides a cured rubber material having a hardnessof not more than 30°, preferably not more than 20°, more preferably notmore than 10°, as measured with an A-type rubber hardness tester, andnot less than 15°, preferably not less than 30°, as measured with anF-type rubber hardness tester, and an impact resilience of not less than50%, preferably not less than 60%, more preferably not less than 70%.

In the foregoing, the A-type rubber hardness tester is a rubber hardnesstester as described in Japanese Industrial Standard (JIS) K 6301-1969.The F-type rubber hardness tester means Asker F rubber hardness testeravailable from Kobunshi Keiki Mfg. Co., Ltd., which is used mainly inmeasuring the hardness of foamed rubber, polyurethane foam or the like.The rubber material of the present invention, though it is a solidrubber material, has a very low hardness, so that the hardness thereofsometimes cannot be measured with the A-type rubber hardness testercommonly ussed in measuring the hardness of a conventional solid rubber.Accordingly, the lower limit of hardness of the rubber material inaccordance with the present invention is defined by the hardness valueas obtained with the F-type rubber hardness tester.

An intermediate hardness between the measuring range of the A-typerubber hardness tester and that of the F-type rubber hardness tester maybe measured with a C-type rubber hardness tester. By the "C-type rubberhardness tester" is meant the one as provided in Japan Society of RubberIndustry Standard SRIS-0101, which is used in measuring suchintermediate hardnesses between the measuring range of the A-type rubberhardness tester and that of the F-type rubber hardness tester. TheC-type rubber hardness tester is used mostly in measuring the hardnessof sponge or soft rubber. The hardness values described herein asobtained with the C-type rubber hardness tester are the values obtainedwith Asker C rubber hardness tester available from Kobunshi Keiki Mfg.Co., Ltd.

The hardness of the rubber material in accordance with the presentinvention may be measured with any of the A-, C- and F-type rubberhardness testers if the measurement is possible with any of these rubberhardness testers. However, if the hardness as measured with the A-typerubber hardness tester is not more than 1°, it is preferable to measurethe hardness with the C-type or F-type rubber hardness tester becausemeasurements with the A-type rubber hardness tester may be accompaniedwith increased errors. Similarly, if the hardness as measurd with theC-type rubber hardness tester is not more than 1°, it is preferable tomeasure the hardness with the F-type rubber hardness tester. If thehardness as measured with the C-type rubber hardness tester is not lessthan 99°, it is preferable to measure the hardness with the A-typerubber hardness tester. Similarly, if the hardness as measured with theF-type rubber hardness tester is not less than 99°, it is preferable tomeasure the hardness with the C-type or A-type rubber hardness tester.The hardness values obtained with the A-type rubber hardness tester, theC-type rubber hardness tester and the F-type rubber hardness tester willhereinafter be referred to as A hardness, C hardness and F hardness,respectively.

The cured rubber material, which has a hardness of from 30° in Ahardness, preferably 20° in A hardness, more preferably 10° in Ahardness to 15° in F hardness, preferably 30° in F hardness and animpact resilience of not less than 50%, preferably not less than 60%,more preferably not less than 70%, is a novel, practically useful rubbermaterial which has not been known heretofore. In the case ofconventional rubber materials adequate for practical use, those with anA hardness of not more than 30° have an impact resilience of less than40%, for example, about 10 to 20%. It is common sense with conventionalrubber materials that the impact resilience of cured rubber decreaseswith a decrease of its hardness. The practical rubber material of thepresent invention which has the specific physical properties, namely ahardness of not more than 30° in A hardness, preferably not more than20° in A hardness, more preferably not more than 10° in A hardness, andan impact resilience of not less than 50%, preferably not less than 60%,more preferably not less than 70%, can have never been anticipated inthe prior art.

The rubber material of the present invention, due to the specialphysical properties thereof mentioned above, is excellent in suchproperties as vibration-proof, sound-proof, shock-absorbing,impact-resisting and cushioning properties, and therefore can adequatelybe used in various ways. Thus, the uses include:

(1) Those mainly utilizing the excellent vibration-proof(vibration-isolating, vibration-absorbing or vibration-damping) property

Various vibration-proof members in record players (turntable rubbersheet, vibration insulator, turntable deadening member, dust coverdamper, cushion between tone arm and cabinet, cushion between head shelland arm shaft, cushion between cartridge and head shell, cushion atmounting place for motor or condenser, stabilizer for disk, cord bush,etc.); cushion at mounting place for speaker unit in speaker cabinet;vibration-proof mat for speaker, rack or the like; insulator orvibration-proof mat for precision instrument or precision apparatus suchas chemical balance, vibration insulator or vibration-proof mat forstand or bench for such instrument or apparatus; vibration-proof (orsound-proof) material for use in floor, wall or the like in building orthe like; vibration insulator or vibration-proof mat for radio set,television set, amplifier, tape recorder, video recorder, telephone,facsimile telegraph, teletypewriter, electronic desk computer, etc;vibration-proof member in dental equipment; vibration-proof member inhandlebar of chain saw, rock drill or the like; pedal rubber ofmotorcycle or motorbike.

(2) Those mainly utilizing the excellent sound-proof (sound-isolating orsound-absorbing) property

Sound-absorbing material in speaker cabinet; muffler forinternal-combustion engine; sound-absorbing material within engine hood;sound-proof (sound-absorbing) mat for indoor or outdoor use;sound-absorbing material in vacuum cleaner; sound-absorbing material inair conditioner; sealing material for sound-proof window;sound-absorbing (sound-proof) material to be applied to windowpane.

(3) Those mainly utilizing the excellent shock-absorbing orimpact-resistance property

Shock absorber such as automobile bumper, fender for use on ship's side,quay wall or the like; a variety of sealing materials (e.g. for door ofcar, building, refrigerator or the like, for trunk compartment of car,for trunk or suitcase); shock-absorbing material in sports field (pole,fence, etc.); attachment rubber for vacuum cleaner mouthpiece; protectorfor use in a variety of sports; shock absorber for use in parachutedescent; joint member of pipe for transport of gas, liquid, powder orthe like; cord bush.

(4) Those mainly utilizing the soft and flexible feel and the excellentcushioning property

Headphone ear pad; rubber eyepiece member in cathode-ray tube, camera,video recorder camera, dustproof goggles, swimming goggles, etc.;medical prosthetic material (artificial breast, artificial heel or thelike); doll; figure-correcting member for use in clothes (pad forbrassiere, corset, men's suit, female dress, etc.); material for makingwet suit or the like; shock-absorbing heel or insole for fracturepatients; material for making shoes [sole material, material for makingshoes themselves (in combination use with cloth, hard rubber, etc.)];rubber end or elbow rest of stick; cushioning material for chair, seatcushion, mattress, bed, etc.

(5) Those contributing to improvement in quality of reproduced sound inaudio equipment

Speaker diaphragm; structural material, interior lining or exteriorlining of speaker cabinet; material of record player box; material ofbelt or pulley for phonomotor; interior or exterior lining of a varietyof musical instruments.

(6) Other uses utilizing the low hardness and high impact resilience.

Non-puncture tire (substitute for a tube and air contained in the tube)or tube itself (solid tire with tire cover) for automobile, motorcycle,motorbike, bicycle, baby buggy, baby car, shopping cart, wheelchair,etc.; rubber caster wheel; core of golf ball; filler in oil welldrilling.

(7) Other uses

Oil fence material (good in oil absorption).

The above-mentioned excellent vibration-proof, sound-proof,shock-absorbing, impact-resisting, cushioning and other properties canbe exhibited only by the cured rubber having the specific physicalproperties, namely a hardness of from 30°, preferably 20°, morepreferably 10° in A hardness to 15°, preferably 30° in F hardness and animpact resilience of not less than 50%, preferably not less than 60°,more preferably not less than 70%. Hardness and impact resilience valuesoutside the above respective ranges are unfavorable because of poorvibration-proof, sound-proof, shock-absorbing, impact-resisting,cushioning and other properties.

The rubber material of the present invention preferably has, in additionto the above physical properties, a tensile strength of 0.1 to 100kg./cm²., more preferably 1 to 50 kg./cm²., an elongation of 50 to1,000%, more preferably 200 to 1,000%, and a specific gravity of 0.8 to1.3, more preferably 0.89 to 1.1.

The cured rubber having the specific physical properties mentioned abovecan be obtained by curing a rubber composition comprising (A) 100 parts(by weight, the same hereinafter) of a rubber component, (B) 5 to 2,000parts, preferably 50 to 2,000 parts, more preferably 100 to 2,000 partsof a factice and (C) 20 to 2,000 parts, preferably 100 to 2,000 parts,more preferably 200 to 2,000 parts of a softening agent. Such a rubbercomposition containing such large amounts of factice and softening agentper rubber component is a novel rubber composition hitherto unknown inthe art. By curing such a novel rubber composition, there can beobtained for the first time the specific cured rubber having a hardnessof from 30°, preferably 20°, more preferably 10° in A hardness to 15°,preferably 30° in F hardness and an impact resilience of not less than50%, preferably not less than 60%, more preferably not less than 70%.For polynorbornene, it is known in the art that a cured rubber having anA hardness of about 7° can be obtained by adding a large amount of asoftening agent to polynorobornene, but the cured rubber, which does notcontain any factice, has an impact resilience of less than 50% andcannot be put into practical use because of intense bleeding tendency.On the contrary, in accordance with the present invention, a largeamount of a factice is employed together with a large amount of asoftening agent, so that bleeding can be inhibited and a practicalrubber material having a low hardness and a high impact resiliencerespectively falling within the above-mentioned specific ranges can beobtained. Moreover, it has now been found that such cured rubber isexcellent in vibration-proof, sound-proof, shock-absorbing, cushioningand other properties, and the material has further specific propertiessuch that it is best suited as a material for making the speakerdiaphargm (reproducing extremely low-pitched sounds and soundingsounds), that it is crushed to pieces upon receiving an excessive impactforce (advantageous in use as a bumper material), and that it can beused as a substitute for tube and air in tire.

The rubber component (A) is not particularly limited. There areexemplified rubber components composed predominantly of one or moremembers of polynorbornene, natural rubber, isoprene rubber, chloroprenerubber, styrene-butadiene rubber, butadiene rubber, butyl rubber,ethylene-propylene rubber, ethylene-propylene-diene rubber, nitrilerubber, acrylic rubber, urethane rubber, chlorinated polyethylene,chlorosulfonated polyethylene, epichlorohydrin rubber, polysulfiderubber, silicone rubber and the like. Regenerated products (e.g. rubberpowder) therefrom are also included. The rubber component may be eitherin solid form (e.g. powder, pellets, blocks, sheets) or in liquid form(e.g. liquid rubber, latex). Among the above exemplified rubbercomponents, the preferred is a rubber component predominantly composedof polynorbornene, the content of polynorbornene being preferably notless than 50% (percent by weight, the same hereinafter), more preferablynot less than 65%, based on the whole rubber component.

The factice as the component (B) includes a variety of factices, forexample, white factice, black factice, amber factice and blue factice,which are prepared by vulcanizing various vegetable oils includinglinseed oil, rapeseed oil, soybean oil, sesame oil, tung oil and castoroil with sulfur or sulfur chloride. Those factices may be used eitheralone or in combination. Especially preferred is a factice obtainable byvulcanization of rapeseed oil.

The softening agent as the component (C) includes oils, plasticizers andother agents having a softening activity. The oils incude those commonlyused as extender oils (softening oils, process oils, etc.) for rubbers,such as aromatic oils, naphthenic oils, paraffinic oils, vegetable oilsand animal oils. Examples of the vegetable and animal oils are castoroil, rapeseed oil, linseed oil, whale oil and fish oil. As plasticizers,there may be used those having a greater solftening capacity among usualplasticizers, for example, dibutyl phthalate, dioctyl phthalate anddioctyl sebacate. Other usable softening agents include liquid rubbersand the like. The softening agents mentioned above may be used eitheralone or in combination of two or more. Use of an oil alone or acombined use of an oil and a plasticizer is generally preferred.

The above-mentioned rubber composition may also contain, besides thecomponents (A) to (C), other usual rubber additives such as filler (e.g.carbon black, zinc oxide), colorant, lubricant (e.g. stearic acid) andantioxidant in such an amount that the above-mentioned physicalproperties are not impaired.

Curing of the above rubber composition can be carried out with any ofusual curing systems. Sulfur curing or sulfurless curing may be adopted.The curing conditions are not critical, hence usual conditions may beused.

A typical example of the above rubber composition, which is suited forsulfur curing, is as follows:

    ______________________________________                                        (Component)           (Parts)                                                 ______________________________________                                        Rubber component      100                                                     Factice               100 to 2,000                                            Softening agent       200 to 2,000                                            Filler                1 to 100                                                Antioxidant           0.5 to 6                                                Sulfur                0.5 to 10                                               Curing accelerator    1 to 20                                                 ______________________________________                                    

For making the rubber material of the present invention adequate for aspecific use, the above-mentioned rubber composition is cured in a shapeadequate for the use in the same manner as in producing usual rubbermoldings. For example, the rubber composition may be either press-cureddirectly in a mold having a cavity of the desired shape and dimensions,or first formed into an uncured molding, for example, by calendering orextrusion, followed by press- or steam-curing of the molding. Injectionmolding is also possible.

Some specific uses of the rubber material of the present invention areillustrated in the following:

(1) Vibration-proof material

In cases where the rubber material of the present invention is used as avibration-proof material for use in vibration-proof members such asrubber sheet for turntable, vibration insulator (vibration-proof rubberfoot) and vibration-proof mat, the shape thereof is not particularlylimited. However, a shape having a large number of projections on a facethereof which will come into contact with other member, preferablyprojections capable of contacting other member substantially at pointsor along lines, is preferred. Such a shape reduces the contact area withthe other member and also causes involvement of air layer among theprojections, so that an enhanced vibration-proof effect can be obtainedas a result of synergism of the air layer and the rubber material of thepresent invention which has the above-mentioned specific properties.

The shape of the projections is not particularly limited, hence variousshapes can be employed. However, from the viewpoint of reducing thecontact area with the other member as much as possible, such a shapethat the area of the head of each projection is as small as possible ispreferable. An embodiment of such a projection has a shape wherein atleast the head of the projection is ridge-shaped so as to allowsubstantially linear contact with the other member. The projectionaccording to this embodiment includes a roof-shaped one, one having asemicircular section and one with a knife edge-shaped head, thelast-mentioned one being especially preferred. Another preferableembodiment has a shape wherein at least the head of the projection ispointed so as to allow substantially point contact with the othermember. In accordance with this embodiment, the projection has shapessuch as a pyramid (which includes a triangular pyramid, a quadrangularpyramid and other polygonal pyramids, the same hereinafter), a cone(which includes an elliptic cone, the same hereinafter), a dome (whichincludes an almost spherical one, a semispherical one, a circularcylinder with a rounded head, etc., the same hereinafter). A projectionhaving a sharp head like a needle is particularly preferred. In theabove-mentioned two embodiments, the only requirement is that at leastthe head of the projection is ridge-shaped or pointed, and the shape ofthe base thereof is not particularly limited. For example, theprojection may have a shape comprising a base having the shape of atruncated pyramid, a truncated cone or the like and a head mountedthereon, the shape of which is, for instance, roof-like, semicircular insection, pyramidal, conical or dome-like. Other shapes than theabove-mentioned ones may also be used as long as the contact area withother member is allowed as small as possible. For example, truncatedpyramidal, truncated conical, pillar-shaped or column-shaped projectionsmay be used. Furthermore, those projections may have at the top thereofa recess or notch which will ensure line or point contact.

The contact area between a projection-bearing face and an other memberis preferably 0.01 to 10%, more preferably 0.01 to 1%, of the contactarea between the face and the other element, provided that the face isprovided with no projections.

The height of the projection is preferably 0.1 to 5 mm., more preferably0.3 to 2 mm.

The projections may be disposed either at random or regularly on theface of the vibration-proof member which comes into contact with another member. Regular disposition may be carried out in the form ofconcentric circles (which include concentric ellipses, concentricpolygons, and the like, the same hereinafter), volute, radial lines,latticework or straight lines, etc. The individual projections may bedisposed either at adequate intervals or in close contact with oneanother. A combination of these manners of disposition may also be used.When the projections are disposed in close contact with one another, theadjacent projections may be connected integrally with each other at thebases thereof. A preferred manner of disposition is such that theprojections are arranged in close contact with one another in the formof concentric circles so that air can be held in spaces defined by thearrays of the projections and an other member which will come intocontact with the vibration-proof member. Such disposition produces amore improved vibration-proof effect.

The projections as mentioned above may be produced integrally with thebody of the vibration-proof member, or they may be produced separatelyand then attached to the body by means such as adhesion.

The vibration-proof member in accordance with the present invention isprovided with the above-mentioned projections on at least one face outof a plurality of faces which will possibly come into contact with othermembers, although all the faces may be provided with the projections.The shape of other contact face of the vibration-proof member with theother member is not particularly limited. Thus, the face may becompletely flat or be provided with concentrically circular, vortical,radial, lattice-like or rectilinear grooves or ribs, or the like. Theface may also be provided with concavities or protrusions having acircular or polygonal shape or the like in plan view and disposedregularly (e.g. in the form of concentric circles, volute, radial lines,latticework or straight lines) or at random.

The vibration-proof member in accordance with the present invention willbe explained hereinafter by referring to three vibration insulators eachprovided with the above-mentioned projections.

The first vibration insulator is an insulator comprising a sheet-like orpillar-like body made of the rubber material of the present invention,the body being provided with a large number of projections on at leastone face out of a plurality of faces thereof which will possibly comeinto contact with other members. Hereinafter such insulator is referredto as insulator (I).

The insulator (I) is illustrated referring to the drawings. FIG. 1 is avertical cross-sectional view showing an example of the insulator (I),FIG. 2 is a plan view thereof, and FIG. 3 is a plan view of the reverseside. The insulator of this example can be used as an insulator forsupporting record player, speaker cabinet, a variety of measuringinstruments, etc. Generally, it is interposed between such equipment orinstrument and the surface for placement thereof.

In FIGS. 1 to 3, numeral 1 is a sheet-like body made of the rubbermaterial of the present invention. That face of the body 1 which is tocome into contact with an other member 2 to be supported by theinsulator, such as record player is provided with a large number ofprojections 4.

In the insulator having the above construction, the body 1 is made ofthe rubber material of the present invention, which has an excellentvibration-absorbing property, and in addition a large number ofprojections 4 are disposed on the contact face of the body 1 with theother member 2 so that the real contact surface area is reduced to agreat extent and at the same time an air layer is interposed between thebody 1 and the other member 2 by the presence of the projections 4.Thus, the transmission of outside vibration to the other member 2supported by the insulator is sufficiently interrupted and as a result,an excellent vibration-proof effect is produced.

In the insulator (I), the projections 4 may have any of the shapesmentioned above. However, the preferred is a shape wherein at least thehead of each projection is ridge-shaped so as to allow substantiallylinear contact with the other member 2 to be supported and a shapewherein at least the head of each projection is pointed so as to allowsubstantially point contact with the other member 2 to be supported.

In the embodiment shown in FIGS. 1 to 3, each projection 4 is aridge-shaped one which is knife edge-shaped at the head and graduallywidened toward the base. The embodiment is an example whereinprojections having such a ridge shape are disposed on a circular plane.Such a ridge-shaped projection is preferable as the projection inaccordance with the present invention, and a projection of this kind ishereinafter referred to as projection 4, unless noted otherwise. Theridge-shaped projections 4 are arranged closely adjacent with oneanother so as to form concentric circles and thereby constitute arrays 5(5a and 5b) of projections. FIG. 4 is an enlarged cross-sectional viewtaken along the line A--A in FIG. 2 and developed on a plane, and FIG. 5is an enlarged partial perspective view of the projection array 5b.

In disposing the ridge-shaped projections 4 in concentric circles, theprojections are generally arranged, as indicated in FIG. 2, in such amanner that the direction of each ridgeline 4a is equal to that of therespective radius of the circle. In this case, as shown in FIGS. 2 and4, the ridgeline 4a of each projection 4 in one projection array 5a andthat of the corresponding projection 4 in another array 5b may be on thesame radius, or, as shown in FIG. 6, they are not on the same radius butthe ridgeline 4a of each projection 4 in one projection array 5a maycorrespond in the direction of the radius of the circle to a valley 4bbetween two adjacent projections 4 in another projection array 5b.Generally, the projections 4 are flush at the tops (4a) thereof with oneanother. However, such arrangement is not always necessary. Thus, forexample, as shown in FIG. 7, an arrangement is possible such that theprojections 4 in the most inner array 5a are highest and the projections4 in arrays 5b and 5c are lower stepwise in that order. An arrangementin a converse manner is also possible. With such arrangements, when theother member 2 supported by the insulator is light in weight, only thoseprojections 4 that belong to the array 5a (or the array 5c) come intocontact with the other member 2, so that the contact area can be morereduced. As the weight of the other member 2 increases, the projections4 belonging to the array 5b and then those belonging to the array 5c (orthe array 5a) come into contact with the other member 2. Furthermore,various other arrangements may be employed. For example, the projections4 in the array 5b may be the highest or lowest. The number of theprojections 4 and the number of projection arrays 5 are not critical.The only requirement is that the projections 4 can support the othermember 2 at their heads. Thus, for example, in the case of a small-sizedinsulator, a single projection array may be sufficient.

The edge portion of the body 1 may be even with the central portion, asshown in FIG. 1, or may descend toward the edge, as shown in FIG. 7. Inthe latter embodiment, the tensile strength of the rubber material iskilled owing to the fact that the edge portion is relatively thin, sothat closer contact of the body 1 with a surface 3 on which theinsulator is placed can be established. In the embodiment shown in FIG.7, the slanting edge portion is provided with a projection array 5c,although said portion may be free of a projection array.

The shape of that face of the body 1 which is to come into contact withthe placement surface 3 is not particularly limited. Thus, the face maybe completely flat or may be provided with projections 4 similar tothose on the face in contact with the other member 2. In a preferredembodiment, the face is provided with one or more concentric grooves 6,as shown in FIG. 3 and FIG. 7. In this embodiment, air is tightly heldwithin the grooves 6, so that a more improved vibration-proof effect canbe produced as a result of synergism of the air and the projections 4 onthe face in contact with the other member 2. Conversely, the face incontact with the placement surface 3 may be provided with projections 4and the face in contact with the other member 2 with concentric grooves6.

The body 1 may be a thin sheet with a thickness of about 1 mm. to about5 mm. Even such a thin body can produce an excellent vibration-proofeffect due to the previously mentioned specific physical properties ofthe rubber material used and the above-mentioned specific shape, ascompared with conventional insulators. It is not always necessary thatthe body 1 is composed of single rubber material. Thus, for example, asshown in FIG. 8, it is possible that the portion 1a is composed of arubber material having an A hardness of 1° and the portion is sandwichedby two portions 1b and 1c each composed of a rubber material having an Ahardness of 9°.

The shape in plan view of the body 1 is not limited to a circle as shownin FIGS. 2 and 3, but may be any of various shapes including an ellipseand a polygon (which includes triangle, quadrangle, pentagon, hexagonand other polygons, the same hereinafter). The body 1 may have a shapeother than a sheet-like one. It may have any of various pillar-like orcolumn-like shapes, including cylinder, elliptic cylinder, polygonalcylinder, truncated cone, truncated polygonal pyramid, etc. The body 1shown in FIG. 9 is a cylinder which has projections 4 on its face incontact with the other member 2 and a concavity 6a on its face incontact with the placement surface 3.

The side face of the cylindrical body 1 may be provided with projections7 similar to the projections 4. FIG. 10 shows an example of arrangementof the projections 7, the figure corresponding to a developed view ofthe side face of the body 1. The projections 7 serve in patterning aswell as in reinforcing the side portion of the cylindrical body 1. Whenthe side face of the body 1 also comes into contact with the othermember 2, the projections 7 play the same role as the above-mentionedprojections 4. For increasing the strength of the side portion of thecylindrical body 1, it is also possible to provide the body 1 with aring-shaped band made of a usual hard rubber, a synthetic resin or ametal and surrounding the body 1, instead of the projections 7.

The insulator (I) may merely be interposed between the other member 2and the placement surface 3, as shown in FIG. 1, or it may be fixed tothe other member 2 through a fixing means such as an embedded bolt 8aand a nut 8b, as shown in FIG. 9. Furthermore, as shown in FIGS. 11 and12, attachment by insertion is also possible. FIG. 11 is a verticalcross-sectional view showing an example of the insulator (I) of theinsertion type, and FIG. 12 is a plan view thereof. In this embodiment,the body 1 has a protrusion 9 on the upper face, and the protrusion 9has a flange portion 10. The flange portion 10 has recesses 10a so thatthe protrusion 9 with the flange portion 10 can easily be inserted intoa hole made in the other member 2 to be supported. However, the recesses10a may be omitted. The flange portion 10 may be provided withprojections 4 on the lower face 10b thereof. In cases where the upperface of the protrusion 9 also comes into contact with the other member2, the upper face may be provided with projections 4.

FIG. 13 is a vertical cross-sectional view illustrating another exampleof the insulator (I), FIG. 14 is a plan view thereof and FIG. 15 is avertical cross-sectional view showing a manner of attachment thereof.The insulator in accordance with this embodiment is useful as cushion atthe mounting place for a motor or condenser in a record player.

In FIGS. 13 to 15, a cylindrical body 1 is provided with an annulargroove 11 formed on the side face thereof and with a hole 12 passingthrough the central part thereof. Projections 4 are disposed on theupper face of the body 1. The body 1 is constructed so that it can beattached to a supporting plate 13 by insertion in a hole in the plateand the edge of the hole in the supporting plate 13 is engaged with theannular groove 11 on the side of the body 1. A hanging bolt 15 isinserted in the hole 12 in the body 1, and a motor 14 is fixedlyconnected to the bolt. A packing indicated by numeral 16 is in contactwith the projections 4 on the upper face of the body 1.

The upper face 11a and/or the lower face 11b of the annular groove 11,which is in contact with the supporting plate 13, may be provided withprojections 4. Similarly, the inside face of the hole 12 in which thehanging bolt 15 is inserted may be provided with projections 7.

In case the body 1 is sheet-like and great in area, the insulator (I)may be used not only as a vibration-proof rubber foot but also as avibration-proof mat.

The second vibration insulator comprises a first vibration-proof memberwhich comes in contact with a surface on which the insulator is placedand is composed of the rubber material of the present invention, and asecond vibration-proof member which comes in contact with an othermember to be supported by the insulator and is composed of the rubbermaterial of the present invention. The first vibration-proof member hasan opening on the upper face thereof and contains a hollow cavityexpanded as compared with the opening, and the second vibration-proofmember has a protrusion having a shape which corresponds to that of thehollow cavity, the protrusion of the second vibration-proof member thusbeing inserted in the hollow cavity of the first vibration-proof member.The contact between the first vibration-proof member and the secondvibration-proof member is established through a large number ofprojections provided either on the surface of the hollow cavity in thefirst vibration-proof member or on the surface of the protrusion of thesecond vibration-proof member. The first vibration-proof member isprovided with a large number of projections on the face in contact withthe surface for placement of the insulator. Such insulator ishereinafter referred to as insulator (II).

Referring to the drawings, the insulator (II) will be illustrated. FIG.16 is a vertical cross-sectional view showing an example of theinsulator (II) and FIG. 17 is a plan view of the bottom thereof. InFIGS. 16 and 17, numeral 21 is the first vibration-proof member, andnumeral 22 is the second vibration-proof member. The vibration-proofmembers 21 and 22 are each composed of the rubber material of thepresent invention. FIG. 18 is a vertical cross-sectional view of thevibration-proof member 21 and FIG. 19 is a plan view thereof. FIG. 20 isa vertical cross-sectional view of the vibration-proof member 22 andFIG. 21 is a plan view thereof.

The vibration-proof member 21 has an opening 21a on the upper facethereof and contains a hollow cavity 21b expanded as compared with theopening. The surface of the hollow cavity 21b is provided with a largenumber of projections 23. The vibration-proof member 21 is also providedwith a large number of projections 4 on the face in contact with thesurface 3 for placement of the insulator. The vibration-proof member 22has a protrusion 22a which has a shape corresponding to that of thehollow cavity 21b in the vibration-proof member 21. The protrusion 22aof the vibration-proof member 22 is inserted under pressure into thehollow cavity 21b in the vibration-proof member 21. The vibration-proofmember 21 and the vibration-proof member 22 are in contact with eachother only through the heads of the projections 23 disposed on thesurface of the hollow cavity 21b. The above-mentioned insulator isconstructed so that it is fixedly attached to an other member 2 to besupported, by means of a bolt 8a embedded in the vibration-proof member22 and a nut 8b.

In the insulator (II) having the above-mentioned construction,transmission of outside vibrations to the other member 2 is inhibited toa satisfactory extent and an excellent vibration-proof effect isproduced, since the rubber material of the present invention is used ineach of the vibration-proof member 21 in contact with the surface 3 forplacement of the insulator and the vibration-proof member 22 in contactwith the other member 2 and further the contact area between thevibration-proof member 21 and the vibration-proof member 22 is reducedby means of the projections 23 and at the same time the contact areabetween the vibration-proof member 21 and the placement surface 3 isreduced by means of the projections 4.

In the insulator (II), the projections 23, which are provided for thepurpose of reducing the contact area between the vibration-proof member21 and the vibration-proof member 22, may be disposed either on thesurface of the hollow cavity 21b in the vibration-proof member 21, as inthe example shown in FIGS. 16 to 21, or on the surface of the protrusion22a of the vibration-proof member 22. It is also possible to providethem on both the surfaces.

In the insulator (II), the projections 4 provided on that face of thevibration-proof member 21 which comes into contact with the placementsurface 3 may be similar to the projections 4 in the insulator (I), andthe arrangement thereof may also be similar to that in the insulator(I). For instance, the projections 4 in the example shown in FIGS. 16 to21 are ridge-shaped and each has a knife edge-shaped head and a widenedbase. In the example, such ridge-shaped projections are disposed in acircular plane. The ridge-shaped projections 4 are disposed inconcentric circles, so that they constitute projection arrays 5 (5a, 5band 5c).

The shape of the projections 23 in the insulator (II) may be similar tothat of the projections 4 in the insulator (I), and the arrangementthereof may also be similar to that in the insulator (I) except that thearrangement surface is a curved surface.

In the insulator (II), the rubber material of the present invention usedin the vibration-proof member 21 and that used in the vibration-proofmember 22 may have either the same physical properties or differentphysical properties. For example, an embodiment may be mentioned whereina rubber material having an A hardness of 1° is used for thevibration-proof member 21 and a rubber material having an A hardness of8° is used for the vibration-proof member 22. Such use of rubbermaterials different in hardness in the vibration-proof member 21 and thevibration-proof member 22 is advantageous in that a more improvedvibration-proof effect can be produced against a finer vibration.

The vibration-proof member 21 in the insulator (II) may be similar inshape to the pillar- or column-shaped body 1 in the insulator (I) exceptthat the member 21 contains a hollow cavity. The vibration-proof member21 may be provided with projections 7 on the side face thereof as in thecase of the insulator (I). It is also possible, as shown in FIG. 22, toprovide the member 21 with a ring-shaped band 24 surrounding the memberand composed of a usual hard rubber, a synthetic resin or a metal,instead of the projections 7. When the upper face of the vibration-proofmember 21 comes into direct contact with the other member 2, the upperface of the vibration-proof member 21 may be provided with projections4, as shown in FIG. 22, in a similar manner as in the case of the facein contact with the placement surface 3. The face of the vibration-proofmember 21 in contact with the placement surface 3 may be furtherprovided with a concavity 25.

The shape of the protrusion 22a of the vibration-proof member 22 is notparticularly limited. The shape includes a spherical one as shown inFIGS. 16, 20 and 21, a truncated cone as shown in FIG. 22, and othervarious shapes such as hemisphere, cylinder, polygonal prism, cone andpolygonal pyramid. The shape of the hollow cavity 21b in thevibration-proof member 21 is made to substantially correspond to theshape of the protrusion 22a of the vibration-proof member 22.

In the insulator (II), it is preferred that the space between the wallof the hollow cavity 21b in the vibration-proof member 21 and theprotrusion 22a of the vibration-proof member 22 is kept air-tight,whereby entrance and exit of air is prohibited. Such a condition canbring about a more improved vibration-proof effect. As an example of themeans for keeping the space air-tight, there may be mentioned use of asealing member 26 capable of tightly coming in contact wiith the upperside face of the vibration-proof member 22, as shown in FIG. 16, for thecase in which projections 23a are disposed on the wall of the opening21a of the vibration-proof member 21 (or at that part of thevibration-proof member 22 which faces the wall of the opening 21a), asshown in FIGS. 16, 18 and 19. When such projections 23a are not providedon the wall of the opening 21a of the vibration-proof member 21 (or atthat part of the vibration-proof member 22 which faces the wall of theopening 21a), it is sufficient that the wall of the opening 21a of thevibration-proof member 21 and that face of the vibration-proof member 22which faces the wall of the opening 21a can come into close contact witheach other.

The means by which the insulator (II) is attached to the other member 2is not critial, but includes the use of an embedded bolt 8a and a nut8b, as shown in FIG. 16, and insertion of the head portion 22b of thevibration-proof member 22 into a hole made in the other member 2, asshown in FIG. 22.

The third vibration insulator comprises a core member, a firstvibration-proof member disposed on the core member and coming intocontact with an other member to be supported by the insulator, whichvibration-proof member is composed of the rubber material of the presentinvention, and a second vibration-proof member disposed under the coremember and coming into contact with a surface on which the insulator isplaced, which second vibration-proof member is composed of the rubbermaterial of the present invention, and that face of the secondvibration-proof member which comes into contact with the placementsurface and/or that face of the first vibration-proof member which comesinto contact with the other member to be supported being provided with alarge number of projections. Such insulator is hereinafter referred toas insulator (III).

Referring to the drawings, the insulator (III) will now be illustrated.FIG. 23 is a vertical cross-sectional view of an embodiment of theinsulator (III), and FIG. 24 is a plan view of the bottom thereof. InFIGS. 23 and 24, numeral 31 is a core member, numeral 32 is a firstvibration-proof member disposed on the core member 31. Thevibration-proof member 32 is to come into contact with an other member 2to be supported by the insulator, for example, a record player. A memberindicated by numeral 33 is a second vibration-proof member disposedunder the core member 31 and is to come into contact with a placementsurface 3 for the insulator. The vibration-proof members 32 and 33 areeach composed of the rubber material of the present invention.

The core member 31 is a hollow body having a top plate 31a and providedwith an annular protrusion 31b on the inside wall of the lower end. Theprotrusion 31b has a shape in section such as wedge, rectangle orsemicircular shape. On the other hand, the upper face of thevibration-proof member 33 is provided with a cylindrical portion 33a.The outer side face of the cylindrical portion 33a has an annular recess33b which corresponds in shape to the annular protrusion 31b of the coremember 31, so that the vibration-proof member 33 is attached to the coremember 31 by insertion. The vibration-proof member 32 is flat and iseither merely placed on the core member 31 or fixed thereto by adhesion.The vibration-proof member 33 is provided with a large number ofprojections 4 disposed on the face in contact with the placement surface3. The above-mentioned insulator is attached to the other member 2 bymeans of a bolt 34a and a nut 34b.

In the insulator (III) having the above-mentioned construction,transmission of outside vibrations to the other member 2 is inhibited toa satisfactory extent and an excellent vibration-proof effect isproduced, since the rubber material of the present invention which isexcellent in vibration-absorbing property is used in each of thatportion of the insulator which comes into contact with the placementsurface 3 and that portion which comes into contact with the supportedother member 2 and at the same time a large number of projections 4 aredisposed on that face of the vibration-proof member 33 which comes intocontact with the placement surface 3 so that the contact area betweenthe insulator and the placement surface 3 is much reduced.

In the insulator (III), the projections 4 disposed on that face of thevibration-proof member 33 which comes into contact with the placementsurface 3 may be similar to the projections 4 in the insulator (I), andthey may be arranged in a manner similar to that described for theinsulator (I). For example, in an embodiment shown in FIGS. 23 and 24,each projection 4 is ridge-shaped and has a knife edge-shaped head 4aand a widened base. In the embodiment, such ridge-shaped projections aredisposed on a circular plane. Thus, the ridge-shaped projections 4 arearranged in concentric circles, forming projection arrays 5 (5a, 5b and5c).

The rubber material of the present invention used in the vibration-proofmember 32 and that used in the vibration-proof member 33 may be the sameor different in physical properties. For example, there may be mentionedan embodiment wherein a rubber material having an A hardness of 8° isused for the vibration-proof member 32 and a rubber material having an Ahardness of 1° is used for the vibration-proof member 33.

The shape of the core member 31 is not critical. For instance, it may bea solid cylinder or prism. However, a hollow body having a top plate 31aas shown in FIG. 23 is usually preferred. The hollow body may be, forinstance, a hollow cylinder or a hollow polygonal prism, the formerbeing usually preferred. By closing the hollow core member 31 at thebottom opening thereof with the vibration-proof member 33, air isconfined and tightly kept in the inside space 35, and the air furtherincreases the vibration-proof effect. The material of the core member 31is not particularly limited. The only requirement is that the materialhas a sufficient rigidity to resist the weight of the other member 2without any undue deformation. Thus, the usable material includes hardrubbers, synthetic resins such as hard polyvinyl chloride and ABS(acrylonitrile-butadiene-styrene) resin, and metals such as iron andaluminum alloy. Among these, hard rubbers are especially preferred. Whena hard rubber is used, an air cushion is formed as a result ofcontribution of the air sealed within the inside space 35 and elasticityof the hard rubber, so that a more favorable vibration-proof effect isproduced.

The means for attaching the vibration-proof member 33 to the core member31 is not critical. Various means other than that described in referenceto the above embodiment may also be employed. For instance, in anexample shown in FIG. 25, the core member 31 is provided with an annulargroove 31c on the bottom face thereof, whereas the vibration-proofmember 33 is provided on the upper face thereof with an annularprotrusion 33c which corresponds to the above-mentioned annular groove31c, so that attachment by insertion is possible. The means ofattachment as illustrated in FIG. 23 may be simplified by omitting boththe annular protrusion 31b of the core member 31 and the annular recess33b of the vibration-proof member 33. Furthermore, the vibration-proofmember 33 may be attached to the core member 31 by such means asadhesion, without using such means for attachment by insertion asmentioned above. That portion of the vibration-proof member 33 whichcarries the load of the other member 2 via the core member 31 preferablyhas a greater thickness than that of the central portion thereof, asshown in FIG. 23 and FIG. 25.

The means for attaching the vibration-proof member 32 to the core member31 is not particualrly limited. It may be sufficient that the member 32is merely placed on the upper face of the core member 31, as shown inFIG. 23. Attachment by insertion is possible when the core member 31 isprovided on the upper face thereof with an annular groove 31d and at thesame time an annular protrusion 32a is formed by bending the edgeportion of the vibration-proof member 32 so as to correspond to theabove-mentioned annular groove 31d, as shown in FIG. 25.

In the insulator (III), the vibration-proof member 32 is preferablyprovided, on the face in contact with the other member 2 or on the facein contact with the core member 31, with projections 4 similar to thoseprovided in the vibration-proof member 33. The insulator (I) having asheet-like body (1) as shown in FIGS. 1 to 5 or FIG. 7 is preferred asthe vibration-proof member 32. FIG. 26 shows an example of the insulator(III) wherein the vibration-proof member 32 has substantially the sameshape as the insulator shown in FIG. 7 has. In the vibration-proofmember 32 shown in FIG. 26, ridge-shaped projections 4 are disposed inconcentric circles on the upper face of the member 32 so as toconstitute projection arrays 5 (5a, 5b and 5c). The height of theprojections 4 is greatest in the array 5a, then decreases gradually orstepwise in the outer array 5b and the most outer array 5c in thatorder. The vibration-proof member 32 is provided on the bottom facethereof with concentric circular grooves 6.

The means for attaching the insulator (III) to the other member 2 is notparticularly limited. Thus, for example, attachment may be performed bymeans of a bolt 34a and a nut 34b, as shown in FIG. 23, or by means ofan embedded bolt 8a and a nut 8b, as shown in FIG. 25.

The above-mentioned insulators (I), (II) and (III), which are excellentin vibration-proof property, can be used satisfactorily as vibrationinsulators for a variety of equipments and instruments. For instance,they can favorably be used for record player, radio set, amplifier,telephone, speaker cabinet, video recorder, facsimile telegraph,teleprinter, television set, car stereo, tape recorder, and variousmeasuring instruments such as chemical balance. When they are used asvibration insulators for a record player, for instance, deterioration insound quality as caused by howling or outside vibration can be preventedto a satisfactory extent, so that high fidelity reproduction of thesounds of the original performance can be achieved. When they are usedas vibration insulators for a chemical balance, for instance, errors inweighing as caused by outside vibration can be eliminated.

The rubber material of the present invention is also useful as thematerial for making a deadening member for turntable.

The turntable in record player is usually made of an aluminum alloy.Since the turntable made of the alloy is light in weight, it tends tovibrate, especially at the start, and also the so-called squealingphenomenon takes place. These lead to deterioration in quality ofreproduced sound. For preventing vibration of the turntable andsquealing at the start, a deadening member composed of hard rubber isattached to the back of the turntable. However, the conventionaldeadening member composed of hard rubber cannot prevent these phenomenato a satisfactory extent.

It has now been found that a deadening member made of the rubbermaterial of the present invention can satisfactorily prevent vibrationof the turntable and squealing at the start. More particularly, thedeadening member composed of the rubber material of the presentinvention makes it possible to attain high quality of reproduced sound,because the rubber material has an excellent vibration-abosorbingproperty so that vibration and squealing at the start of the turntablecan be prevented to a satisfactory extent and because the rubbermaterial efficiently absorbs vibrations caused, for example, by thedriving motor, which is responsible for the excellentvibration-absorbing property thereof, so that transmission of suchvibrations to the record can be prevented.

In using the rubber material of the present invention as the material ofa deadening member, the shape thereof is not critical. Some examples areillustrated by referring to drawings.

FIG. 27 is a perspective view illustrating an example of the deadeningmember wherein the rubber material of the present invention is used.FIG. 28 is a cross-sectional view illustrating the state that thedeadening member is attached to a turntable.

Numeral 41 indicates a disk-shaped deadening member composed of therubber material of the present invention. At the center of the deadeningmember, there is made a hole 42 into which the center shaft 44 of aturntable 43 is to fit. The deadening member 41 is attached to the backof the turntable 43, for instance, by the use of an adhesive.

When the deadening member 41 is disk-shaped, the thickness thereof isusually about 1 mm. to about 10 mm.

The shape of the deadening member 41 is not limited to the disk-like onementioned above, but various shapes may be employed. For instance, thedeadening member may be ring-shaped, as shown in FIG. 29. Furthermore,it may be constituted by a plurality of divided portions or segments,for example, segments 41a, 41b, 41c, 41d, 41e and 41f, as shown in FIG.30.

The means for attaching the deadening member 41 to the turntable 43 isnot particularly limited, but generally adhesion using an adhesive ispreferred. When the deadening member 41 is ring-shaped, for instance, asshown in FIG. 29, it may be attached to the turntable 43 through anengaging member (not shown) provided on the flange 45 of the turntable43.

It is not necessary that the whole body of the deadening member 41should be composed of single rubber material, but the deadening membermay be composed of a plurality of rubber materials having differentphysical properties. For example, a laminated sheet comprising a sheetof a rubber material having an A hardness of 5° and a sheet of a rubbermaterial having an A hardness of 15° may be adopted.

(2) Shock-absorbing material

The rubber material of the present invention is useful as the materialconstituting a bumper for use in automobile, etc.

A steel bumper has so far been used in the automobile. In response toincreasing safety requirement, a bumper made of urethane rubber also hasbeen introduced. However, even such an urethane rubber bumper isunsatisfactory in respect to shock absorption.

The rubber material of the present invention is much superior as thebumper material to the conventional urethane rubber. This is supposedlydue to the fact that the rubber material of the present invention is lowin hardness and high in impact resilience as compared with theconventional urethane rubber. This becomes clear from the indirectexperiment mentioned in the following:

Experiment

Physical properties of a rubber material of the present invention, aconventional urethane rubber and a typical example ofethylene-propylene-diene rubber (hereinafter referred to as EPDM) whichis lower in hardness but higher in impact resilience than the urethanerubber are shown in Table 1. The rubber material of the presentinvention used herein is the one in accordance with Example 4 givenhereinafter.

                  TABLE 1                                                         ______________________________________                                                   Rubber material                                                                                     Conventional                                              The in- Conventional                                                                              urethane                                     Physical property                                                                          vention EPDM rubber rubber                                       ______________________________________                                        A hardness (degree)                                                                        6       70          90                                           Impact resilience (%)                                                                      81      34          29                                           Tensile strength                                                                           18      126         455                                          (kg./cm..sup.2)                                                               Elongation (%)                                                                             398     370         550                                          Specific gravity                                                                           0.977   1.21        1.27                                         ______________________________________                                    

The rubber material of the present invention and EPDM were selected fromthe rubber materials shown in Table 1 and cylindrical test pieces, 29mm. in diameter and 12.5 mm. in height, were prepared therefrom. Eachtest piece was placed in a destructive tester and subjected to pressureby a press, and the influence of each test piece upon the destructivetester was examined.

The tester is schematically illustrated in FIG. 31. In FIG. 31, numeral61 is a rubber test piece, numeral 62a is a male mold of the destructivetester, numeral 62b is a female mold of the destructive tester andnumeral 63 is a press. The male and female molds 62a and 62b are made ofa rolled steel for general constructions as specified in JIS G 3101.

Each test piece was placed in the above-mentioned tester, and subjectedto pressure in a manner as shown in FIG. 32 for the test piece of therubber material of the present invention or as shown in FIG. 33 for thetest piece of EPDM.

When a pressure of 160 kgf./cm². was applied to the test piece of therubber material of the present invention, the thickness of the testpiece was reduced from the orginal 12.5 mm. to 9 mm. The pressure hardlyexceeded 160 kgf./cm². The destructive tester 62a, 62b did not revealany change therein.

In the case of the EPDM test piece, a pressure of 210 kgf./cm². causedalmost no compression of the test piece, but instead, the destructivetester 62a, 62b was destructed as shown in FIG. 34.

According to the above test, the conventional EPDM caused deformation ofthe steel tester at a pressure of 210 kgf./cm². This fact indicates thatsuch a rubber material high in hardness and low in impact resilience asEPDM cannot absorb effectively outside pressure. On the other hand, therubber material of the present invention did not cause any change in thesteel tester an did not allow easy rise in press pressure to 160kgf./cm². and above. These facts suggest that the rubber material of thepresent invention, due to the low hardness and high impact resiliencethereof, can efficiently absorb outside pressure. The same can be saidof the impact resistance, and consequently the rubber material of thepresent invention, which is low in hardness but high in impactresilience, is superior as a shock-absorbing material forshock-absorbing members such as bumper, to EPDM which is high inhardness and low in impact resilience. As for the conventional urethanerubber, the data shown in Table 1 clearly indicate that this rubber ishigher in hardness and lower in impact resilience than EPDM, andtherefore the urethane rubber is supposed to be more inferior incapacity of absorbing impact force.

Another characteristic feature of the rubber material of the presentinvention is that when subjected to an excessive impact force of aboutmore than 100 kg./cm²., it is broken to pieces. This property isadvantageous when the rubber material is used in making an automobilebumper. Thus, when an automobile is exposed to an impact force whichwould be fatal to humans in the automobile, the bumper composed of therubber material of the present invention is broken to pieces, wherebythe impact force is converted to kinetic energy of the broken pieces andthe impact force against the automobile body and human bodies is sharplyreduced.

In case the rubber material of the invention is used as a material ofshock-absorbing members such as bumper, it is particularly preferredthat the rubber material has an A hardness of 5° to 15°, an impactresilience of not less than 60%, and if necessary, further a tensilestrength of 10 to 50 kg./cm². and an elongation of 300 to 600%.

In using the rubber material of the present invention as a material ofbumper, the shape or the like is not particularly limited. Some examplesare explained by referring to drawings.

FIG. 35 is a plan view illustrating an example of the bumper wherein therubber material of the present invention is used. FIG. 36 is an enlargedcross-sectional view taken along the line B--B in FIG. 35. In FIGS. 35and 36, numeral 64 is a bumper body comprising a core body 65 made ofthe rubber material of the present invention and a covering 66 enclosingthe core body. A reinforcing member 67 composed of a material such assteel, hard rubber or hard synthetic resin is embedded in the core body65 substantially over the whole length of the core body. To thereinforcing member 67 are connected fixing membes 68, 68 for attachingthe bumper body 64 to the chassis of the automobile.

The examples of the material constituting the covering 66 are hardrubbers (e.g. having an A hardness of not less than 40°, preferably notless than 60°) such as urethane rubber, EPDM and styrene-butadienerubber, and hard synthetic resins. Since the covering 66 is provided forthe purpose of protecting the soft core body 65 composed of the rubbermaterial of the present invention, the thickness of the covering may beabout 1 mm. to about 5 mm. The covering 66 may be omitted.

The thickness (as measured in the horizontal direction) of the core body65 is about 30 mm. to about 200 mm. for practical use, although agreater thickenss might be preferred from the viewpoint of impactresistance.

The reinforcing member 67 need not be embedded in the core body 65 butmay be attached to the rear face of the bumper body 64, for instance, asshown in FIG. 37. Attachment in that case may be performed by variousmeans such as insertion, adhesion and screwing.

The bumper body 64 may also be attached to a ready-made steel bumper orthe like directly. In that case, the reinforcing member 67 may beomitted.

The rubber material of the present invention is useful not only inmaking an automobile bumper but also in making a variety ofshock-absorbing members. Important examples are fenders for use inship's side, quay wall and the like, and shock absorbers in sports fieldfor protecting players from damages upon bumping.

(3) Sealing material

The rubber material of the present invention, due to the excellentshock-proof and shock-absorbing properties thereof, is useful as asealing material for a variety of uses, for example, sealing members forthe doors of automobile, building, refrigerator, etc.

A conventional sealing member for automobile door is usually composed ofsponge rubber. The sponge rubber is produced by foaming a rubbermaterial originally having a high hardness and a low impact resilience(e.g. an A hardness of 60° to 70° and an impact resilience of 30 to 35%)and has a reduced hardness as a result of interposition of air, but theimpact resilience is considerably low. In case that such sponge rubberis used as a sealing material, the cellular structure, when once brokenby repeated opening and closing of the door, will lose the property oflow hardness, and the material will then be unable to function as asealing material. If fingers are caught in the door, an impact forcewill be exerted directly on the fingers because of the low impactresilience of the sealing material, whereby the possibility of thefingers being damaged is high.

In contrast thereto, a sealing member comprising the rubber material ofthe present invention does not show any decrease in performance due todestruction of the cellular structure as in the sponge rubber butendures semipermanently, since the rubber material itself is a solidrubber having a low hardness and a high impact resilience. Even whenfingers are caught in the door, the impact force, which otherwise wouldact upon the fingers, is buffered as a result of the high impactresilience of the rubber material, whereby the possibility of injury ismuch reduced.

In using the rubber material of the invention as a material of sealingmembers, the shape or the like is not particularly limited. Thus, forexample, such a shape as shown in FIGS. 38 to 39 may be used. FIG. 38 isa partial perspective view of an example of the sealing member whereinthe rubber material of the present invention is used. FIG. 39 is anenlarged cross-sectional view taken along the line C--C in FIG. 38. InFIGS. 38 to 39, numeral 71 is a sealing member in the form of a band.The sealing member 71 is composed of a core body 72 made of the rubbermaterial of the present invention and a covering 73. Examples of thematerial of the covering 73 are usual soft rubbers such as urethanerubber, EPDM and styrene-butadiene rubber, and soft synthetic resinssuch as polyvinyl chloride. The shape in section of the sealing member71 may be modified in various ways depending on the particular usethereof.

(4) Cushioning materials

By virtue of its excellent cushioning properties, the rubber material ofthe present invention can be used with advantage for various kinds ofcushioning members, e.g. as those of chair, bed, mattress, etc.

While sponge rubber has been conventionally employed for a cushioningmember, this material is low in hardness but low in impact resilienceand not necessarily good in cushioning properties as already notedhereinbefore. Taking a sponge rubber mattress as an example, it has onlysuch a low impact resilience that it is virtually devoid of cushioningaction when its thickness is small. Even when the thickness is large,the human body completely sinks into the mattress as a whole and as aresult, the matrress does not display as a cushioning performance asmight be desired.

In contrast, the rubber material of the present invention, when used asa cushioning member, displays an excellent cushioning performance due toits low hardness and high impact resilience and even when its thicknessis comparatively small, the rubber material discharges its missionadequately as a cushioning member.

In using the rubber material of the present invention as a cushioningmember, there is no particular limitation on its shape but the shapeshown as an example in FIG. 40 may be used. FIG. 40 is a perspectiveview showing an embodiment of the cushioning member in which the rubbermaterial of the present invention is used. Indicated by numeral 81 is aplanar cushioning member made of the rubber material of the presentinvention, which member is composed of a single rubber material.

In using the rubber material of the present invention as a cushioningmember, a plurality of layers made of rubber materials having differentphysical properties may be used in laminated construction. For example,as illustrated in FIG. 41, the cushioning member may assume athree-layer construction, a core layer 82 which is made of a rubbermaterial of the present invention having comparatively low hardness andlow impact resilience (e.g. an F hardness of 60°, an impact resilienceof 55%) with an upper layer 83 and a lower layer 84 being made of arubber material of the present invention having comparatively highhardness and high impact resilience (e.g. an A hardness of 8°, an impactresilience of 70%).

(5) Tires

By virtue of its low hardness and high impact resilience, the rubbermaterial of the present invention is useful in such applications asnon-puncture tires, solid tires, etc.

There have been known tubeless tires each comprising a tire body and asticky rubber layer secured to the inner surface thereof so that even ifthe tire is penetrated by a nail, for instance, the air within the tirewill not escape out. However, even if the damage is serious and the tirecannot heal on its own, the inside air excapes and, at times, a burst orother serious accident may take place. Moreover, on a rugged roadsurface, the deformation of the rim flange could result in air leaks.Then, these tires are of limited utility.

However, with the rubber material of the present invention, there can beproduced perfect non-puncture tires, completely free from theabove-mentioned disadvantages of the conventional tubless tires.

The production process for this non-puncture tire is illustrated in theplan view of FIG. 42 and the cross-sectional view of FIG. 43 (takenalong the line D--D of FIG. 42). Thus, the rubber material of thepresent invention is used to fabricate a ring member 91 having asubstantially circular cross-section and sized to fit closely into thetire. Then, the ring member 91 is fitted into the tire 92 and a rim 93is set in position, as shown in FIG. 44.

Unlike the conventional tube-tire and tubeless tire, the non-puncturetire described above does not include air inside thereof but, instead,contains the ring member 91 made of the rubber material of the presentinvention, with the result that there is no fear of a puncture even if anail pierces the tire. Moreover, even if a serious accident such as atear of the tire takes place, the ring member 91 inside the tire 92bears the load till the car has skidded to a stop, so that one can avoidtragedies such as violent collision and fall which would otherwiseresult from the impossibility of steering due to a burst of the tire.

Furthermore, since the non-puncture tire mentioned above is such thatits ring member 91 is made of the rubber material of the presentinvention which has low hardness and high impact resilience, it has acushioning property at least comparable or even superior to that of theconventional tube-tire and tubeless tire.

In addition, in the case of this non-puncture tire whose ring member 91bears a part of the load, the amount of the reinforcing member employedin the tire 92 can be reduced so that the tire itself may be of moreeconomical grade.

While the above-mentioned ring member 91 may be made of a single rubbermaterial as shown in FIG. 43, it may also be made of a plurality ofrubber materials having different physical properties. For instance, asillustrated in FIG. 45, the core 91a may be made of a rubber material ofthe present invention which has comparatively high hardness and highimpact resilience (e.g. an A hardness of 9°, an impact resilience of70%) and the shell or peripheral portion 91b made of a rubber materialof the present invention which has comparatively low hardness and lowimpact resilience (e.g. an A hardness of 1°, an impact resilience of60%). The above different rubber materials may be used in a reversedrelation. These products display a stable cushioning performance over abroad range of low speed to high speed. Alternatively, as shown in FIGS.46 and 47, the ring member 91 may be divided into two segments (or threeor more segments) along a plane perpendicular to its radius and thetread-side segment 91c is made of a rubber material of the presentinvention which has comparatively high hardness and high impactresilience (e.g. an A hardness of 9°, an impact resilience of 70%) withthe rim-side segment 91d being made of a rubber material of the presentinvention which has comparatively low hardness and low impact resilience(e.g. an A hardness of 1°, an impact resilience of 60%). In this case,these rubber materials may be used in a reversed relation.

The above-described non-puncture tire can be used advantageously withautocycles, motorbikes, bicycles, wheel-chairs, etc. as well asautomobiles. In applications which do not involve too large loads, suchas motorcycles, motorbikes, bicycles, wheel-chairs, etc., a hollow space91e may be provided within the ring member 91 as illustrated in FIG. 48.

The rubber material of the present invention is also suitable for solidtires which are used in baby buggies, baby cars, shopping carts,carriages used in factories and warehouses, and the like.

While conventional solid tires are made of materials such as naturalrubber, styrene-butadine rubber and urethane rubber, these tires areinvariably high in hardness and low in impact resilience and, therefore,quite unsatisfactory in cushioning performance. Use of the low hardness,high resilience rubber material of the present invention instead of suchconventional rubbers enables one to obtain solid tires having excellentcushioning properties.

FIG. 49 is a cross-sectional view showing an embodiment of the solidtire using the rubber material of the present invention. Indicated bynumeral 94 is a ring core having a substantially circular cross-sectionwhich is made of the rubber material of the present invention. The ringcore 94 is covered with a cover member 95. The tread (ground contact)face of the cover member 95 is provided with anti-slip grooves 95a,while the opposite side of the member 95 is provided with an ear portion95b adapted to engage a rim 96. Like the ring member 91 mentionedpreviously, this ring core 94 may also be made of rubber materialshaving different physical properties (cf. FIGS. 45 to 47) or a hollowspace may also be provided therein (cf. FIG. 48). The cover member 95may be made of any of usual rubber materials such as styrene-butadienerubber, urethane rubber, EPDM, and a blend of natural rubber, butadienerubber and styrene-butadiene rubber.

The solid tire using the rubber material of the present invention hassuch an improved cushioning property that it can be appliedadvantageously to such equipments as bicycles, motorbikes andwheel-chairs, where solid tires have so far been considered unusable.

The rubber material of the present invention will be explained in moredetail by referring to Examples.

EXAMPLES 1 TO 8

Cured rubber sheets were produced using the rubber compositions shown inTable 2.

The rubber component was first scoured at about 60° C. and then kneadedwith other components by means of a Banbury mixer. The resultant wasfurther kneaded with a roll and sheeted out to give an uncured rubbersheet of about 10 mm. thick. A sheet of a desired dimension was cut outfrom the sheet and cured by a press machine with a given mold under apressure of 150 kg./cm². at 155° C. for 20 minutes to give a curedrubber sheet.

Test pieces were cut out from the cured rubber sheet and variousphysical properties were measured on the test pieces. The resultsthereof are shown in Table 3. Measurements of impact resilience, tensilestrength and elongation were conducted according to JIS K 6301-1969.

                                      TABLE 2                                     __________________________________________________________________________    Rubber composition (in parts)                                                               Example No.                                                     Components    1  2  3  4  5  6  7  8                                          __________________________________________________________________________    Norsorex 150NA (Note 1)                                                                     250                                                                              250                                                                              250                                                                              250                                                                              250                                                                              250                                                                              -- --                                         Norsorex (Note 2)                                                                           -- -- -- -- -- -- 80 75                                         Nipol SBR 1712 (Note 3)                                                                     -- -- -- -- -- -- 27.5                                                                             --                                         Esplene 505 (Note 4)                                                                        -- -- -- -- -- -- -- 25                                         DOG Factice F10 (Note 5)                                                                    300                                                                              240                                                                              120                                                                              225                                                                              230                                                                              200                                                                              420                                                                              330                                        Sunthene 255 (Note 6)                                                                       120                                                                              130                                                                              280                                                                              410                                                                              400                                                                              -- 560                                                                              450                                        Sundex 790 (Note 7)                                                                         -- -- -- -- -- 1000                                                                             -- --                                         Rapeseed oil  -- -- -- -- -- 15 -- --                                         Dioctyl phthalate                                                                           -- 10 -- 45 50 35 -- 80                                         FEF carbon    -- -- 50 50 50 -- 40 80                                         MT carbon     35 -- -- -- -- 50 -- --                                         SRF carbon    -- 40 -- -- -- -- -- --                                         Zinc oxide    5  5  5  5  5  5  5  5                                          Stearic acid  1  1  1  1  1  1  1  1                                          Sumilizer MDP (Note 8)                                                                      -- -- 2  2  -- -- 1  1                                          Antioxidant DDA (Note 9)                                                                    1  1  -- -- 2  2  -- --                                         Suntight S (Note 10)                                                                        1  1  -- -- 1  1  -- --                                         Sulfur        2  2  2  2.5                                                                              2.5                                                                              2.5                                                                              2.5                                                                              2.5                                        Sunceller CZ (Note 11)                                                                      6  8  9  10 8  10 10 10                                         __________________________________________________________________________     Note 1: Polynorbornene (Norsorex, average molecular weight of not less        than 2 × 10.sup.6) extended with 150 parts of naphthenic oil per 10     parts of polynorbornene, sold by Nippon Zeon Co., Ltd. (Norsorex:             registered trademark)                                                         Note 2: Polynorbornene (average molecular weight of not less than 2           × 10.sup.6) sold by Nippon Zeon Co., Ltd.                               Note 3: Styrenebutadiene rubber extended with 37.5 parts of a high            aromatic oil per 100 parts of the rubber, made by Nippon Zeon Co., Ltd.       Note 4: Ethylenepropylene-diene rubber made by Sumitomo Chemical Co., Ltd     Note 5: Amber sulfur factice made by D. O. G. Deutsche Oelfabrick Ges. f.     Chem. Erz. mbh & Co.                                                          Note 6: Naphthenic oil made by Japan Sunoil Co., Ltd.                         Note 7: Aromatic oil made by Japan Sunoil Co., Ltd.                           Note 8: 2,2'-Methylenebis(4-methyl-6-tert. butylphenol) made by Sumitomo      Chemical Co., Ltd.                                                            Note 9: Diphenylamine antioxidant made by Bayer A. G.                         Note 10: Microcrystalline wax made by Seiko Kagaku Kabushiki Kaisha           Note 11: Curing accelerator made by Sanshin Kagaku Kabushiki Kaisha      

                                      TABLE 3                                     __________________________________________________________________________                         Impact                                                                             Tensile                                             Ex.                                                                              Hardness (degree) resilience                                                                         strength                                                                            Elongation                                                                          Specific                                No.                                                                              A hardness                                                                          C hardness                                                                          F hardness                                                                          (%)  (kg./cm..sup.2)                                                                     (%)   gravity                                 __________________________________________________________________________    1  23    --    --    73   16    293   0.999                                   2  18    --    --    71   21    283   0.997                                   3  9     --    --    74   10    281   0.987                                   4  6     --    --    81   18    398   0.977                                   5  1     11    73    63   6.5   387   0.977                                   6  --    --    31    51   0.3   490   1.004                                   7  5     --    --    67   2     161   0.945                                   8  7     --    --    55   5     155   0.979                                   __________________________________________________________________________

EXAMPLES 9 TO 15

Cured rubber sheets were prepared in the same manner as in Examples 1 to8 except that the rubber compositions shown in Table 4 were used. Thephysical properties were measured on the obtained cured rubber sheets.The results thereof are shown in Table 5.

                                      TABLE 4                                     __________________________________________________________________________    Rubber composition (in parts)                                                                 Example No.                                                   Components      9  10 11 12 13 14 15                                          __________________________________________________________________________    Nipol SBR 1712  137.5                                                                            137.5                                                                            -- -- -- -- --                                          Nipol IR 2200 (Note 1)                                                                        -- -- 100                                                                              -- -- -- --                                          Natural rubber  -- -- -- 100                                                                              -- -- --                                          Nordel 1040 (Note 2)                                                                          -- -- -- -- 100                                                                              -- --                                          Baypren 112 (Note 3)                                                                          -- -- -- -- -- 100                                                                              --                                          Millathane 76 (Note 4)                                                                        -- -- -- -- -- -- 100                                         DOG factice F 10                                                                              200                                                                              230                                                                              200                                                                              250                                                                              250                                                                              -- --                                          DOG factice NP 17 (Note 5)                                                                    -- -- -- -- -- 240                                                                              200                                         DOG factice DS · SOFT (Note 6)                                                       -- -- 15 -- -- -- --                                          Sunthene 255    200                                                                              200                                                                              165                                                                              240                                                                              200                                                                              200                                                                              250                                         Sunpar 110 (Note 7)                                                                           -- -- 70 -- -- -- --                                          Thiokol TP-95 (Note 8)                                                                        -- -- -- -- -- -- 10                                          SRF carbon      -- -- 5  -- -- -- --                                          MT carbon       20 60 -- 80 50 45 --                                          Light calcium carbonate                                                                       -- -- -- -- -- -- 10                                          Zinc oxide      5  5  5  5  5  -- --                                          Magnesia        -- -- -- -- -- 4  --                                          Zinc stearate   -- -- -- -- -- -- 0.5                                         Stearic acid    1  1  1  1  1  1  --                                          Antioxidant DDA 2  2  1  1  1  1  --                                          Suntight S      1  1  1  1  1  1  --                                          Sulfur          2  2  2.2                                                                              2  2.5                                                                              2  1.5                                         Sunceller CZ    4  4  2  -- -- -- --                                          Nocceler DM (Note 9)                                                                          -- -- -- 2.7                                                                              -- -- 3                                           Nocceler D (Note 10)                                                                          -- -- -- 0.7                                                                              -- -- --                                          Nocceler TT (Note 11)                                                                         -- -- -- 0.4                                                                              1.2                                                                              -- --                                          Nocceler M (Note 12)                                                                          -- -- -- -- 2  -- 2                                           Nocceler TRA (Note 13)                                                                        -- -- -- -- 1.2                                                                              -- --                                          Nocceler DT (Note 14)                                                                         -- -- -- -- -- 1.1                                                                              --                                          Nocceler TS (Note 15)                                                                         -- -- -- -- -- 1.1                                                                              --                                          Thiokol ZC 456 (Note 16)                                                                      -- -- -- -- -- -- 1                                           __________________________________________________________________________     Note 1: Isoprene rubber made by Nippon Zeon Co., Ltd.                         Note 2: Ethylenepropylene-diene copolymer made by E. I. Du Pont de Nemour     & Co.                                                                         Note 3: Chloroprene rubber made by Bayer A. G.                                Note 4: Urethane rubber made by Technical Sales & Engineering Inc.            Note 5: Amber sulfur factice made by D. O. G. Deutsche Oelfabrick Ges. f.     Chem. Erz. mbh & Co.                                                          Note 6: Amber soft sulfur factice made by D. O. G. Deutsche Oelfabrick        Ges. f. Chem. Erz. mbh & Co.                                                  Note 7: Paraffinic oil made by Japan Sunoil Co., Ltd.                         Note 8: Plasticizer made by Thiokol Corp.                                     Note 9: Curing accelerator made by Ouchi Chemical Industry Co., Ltd.          Note 10: Curing accelerator made by Ouchi Chemical Industry Co., Ltd.         Note 11: Curing accelerator made by Ouchi Chemical Industry Co., Ltd.         Note 12: Curing accelerator made by Ouchi Chemical Industry Co., Ltd.         Note 13: Curing accelerator made by Ouchi Chemical Industry Co., Ltd.         Note 14: Curing accelerator made by Ouchi Chemical Industry Co., Ltd.         Note 15: Curing accelerator made by Ouchi Chemical Industry Co., Ltd.         Note 16: Curing accelerator made by Thiokol Corp.                        

                                      TABLE 5                                     __________________________________________________________________________                         Impact                                                                             Tensile                                             Ex.                                                                              Hardness (degree) resilience                                                                         strength                                                                            Elongation                                                                          Specific                                No.                                                                              A hardness                                                                          C hardness                                                                          F hardness                                                                          (%)  (kg./cm..sup.2)                                                                     (%)   gravity                                 __________________________________________________________________________     9 9     30    --    62   8     258   1.009                                   10 18    46    --    59   21    364   1.016                                   11 8     28    --    64   6     330   0.921                                   12 23    51    --    62   5.4   223   0.984                                   13 6     25    --    52   7     241   0.971                                   14 --    10    69    51   3.6   322   1.026                                   15 4     22    --    61   2     182   1.008                                   __________________________________________________________________________

EXAMPLE 16

The steel front bumper was detached from a compact passenger car (totaldead weight 640 kg.) (hereinafter referred to as car A) and using thebumper as a mold, a rubber bumper was fabricated of the rubber materialof the present invention.

The rubber composition according to Example 4 was filled into theabove-mentioned steel bumper and the whole was wrapped up in a wetcloth. This was then put in a vulcanizing can, in which it wassteam-cured at 140° C. for 60 minutes. The rubber bumper was then takenout from the mold. The rubber bumper thus produced weighed 4.2 kg. andhad a maximum thickness (along the horizontal direction) of 40 mm.

This bumper was subjected to the following impact test.

(1) Purpose of the test

While a collision of cars takes place often when the relative speed ofvehicles is about 4.8 km. to about 16 km./hour, for example, at steeringin parking areas, at starting the car or in a traffic jam, even such amild collision results in substantial damages to cars and driver andpassengers. This has by now been such a serious problem in the UnitedStates of America that governmental standard regulations have beenestablished which require car manufacturers to build cars which would atleast resist a collision impact to the rear bumper at a vehicle speed of4.8 km./hour and a collision impact to the front bumper at a vehiclespeed of 8.0 km./hour. The present test is based on the above-mentionedstandard regulations.

(2) The procedures of the test

The rubber bumper produced above was secured to the front of the frontbumper of the car A at four positions by means of cloth bands. The car Aand another compact car (total dead weight 1075 kg; equipped with steelbumpers) (hereinafter referred to as car B) were positionedfront-to-front at a distance of 5 meters and 3 passengers boarded intoeach car (the total weight of 3 passengers was about 180 kg. for eachcar). The car A was kept standing still with its handbrake disengagedand the car B was driven toward the car A to cause a collision at aspeed of about 10 km./hour.

(3) Results of the test

Regarding the car A, the 3 passengers felt a slight impact but the caritself was not injured or damaged at all. Of course, the rubber bumperof the present invention was not affected, either.

The car B was not damaged at all and the 3 passengers of the car Bhardly felt any impact.

EXAMPLE 17

The rubber composition of Example 4 was presscured under the sameconditions as Examples 1 to 8 to produce a ring member 91 having theconfiguration shown in FIGS. 42 to 43. The ring member 91 had an innerdiameter of 350 mm. and a sectional diameter of 50 mm.

The front and rear wheels of a commercial motorbikes were removed, thetube was taken out from each tire and, in place of the tube, theabove-mentioned ring member was fitted as illustrated in FIG. 44. Thetires thus fitted with the ring members were mounted on theabove-mentioned motorbike and 10 drivers were instructed to drive themotorbike as trials. For control purposes, they were also instructed totest-drive a similar motorbike with the intact tires (i.e. equipped withtube-tires).

All the drivers rated the tires equipped with the ring members of thepresent invention by far superior to the tube-tires in driving comfort.The tires equipped with the ring members of the present invention showedespecially a high performance on unpaved roads by absorbing vibrationsfrom rugged surfaces effectively.

When the above-mentioned two motorbikes were driven on a road over whichnails has been scattered, the tires equipped with the ring members ofthe present invention were not affected at all and the driving comfortwas not altered, either. In contrast, the tube-tires underwentpunctures, thus making further driving impossible.

EXAMPLE 18

Using the rubber compositions of Examples 3 and 5, the ring member 91having the configuration illustrated in FIGS. 42 and 45 wasmanufactured. The core 91a of the ring member was made of the rubbercomposition of Example 3 and the peripheral portion 91b was made of therubber composition of Example 5. The ring member 91 had an innerdiameter of 350 mm. and a sectional diameter of 50 mm., and the core 91ahad a sectional diameter of 25 mm.

The above ring member was fitted to the tire of a motorbike in the samemanner as in Example 17 and the motorbike was test-driven. The testshowed an excellent driving comfort. The tire was found even superior tothe tire of Example 17 especially at a high driving speed of about 30km./hour.

EXAMPLES 19 AND 20

Two different ring members 91 were prepared in the same manner as inExample 17 from the rubber compositions of Examples 2 and 7. Each ringmember was fitted to the tires of a motorbike and the motorbike was thentest-driven. The results showed an excellent driving comfort.

EXAMPLE 21

Using the rubber composition of Example 4 [for the core body 72] and therubber composition of Table 6 [for the covering 73], a car door seal 71having the configuration of FIGS. 38 and 39 was fabricated. The rubbercomposition for the core body and the rubber composition for thecovering were simultaneously extruded with an extruding machine toproduce a cord-shaped product which was then steam-cured in avulcanizing can at 150° C. for 40 minutes. The seal 71 had a thicknessof about 10 mm., a width of about 15 mm. and a covering thickness of 1mm.

                  TABLE 6                                                         ______________________________________                                        Rubber for covering                                                           ______________________________________                                        Rubber composition (in parts)                                                 Nipol SBR 1712       137.5                                                    Sundex 790           20                                                       HAF carbon           80                                                       Zinc oxide           4                                                        Stearic acid         1                                                        Antioxidant DDA      2                                                        Suntight S           4                                                        Sulfur               1.5                                                      Sunceller CZ         1.8                                                      Physical property                                                             A hardness (degree)  57                                                       Impact resilience (%)                                                                              40                                                       Tensile strength (kg./cm..sup.2)                                                                   237                                                      Elongation (%)       620                                                      ______________________________________                                    

The above door seal was fitted in position as the door seals of acompact passenger car and subjected to a door operation test. The doorseal was not damaged at all, retaining its original cushioningperformance and airtight performance fully even after the test.Moreover, when jammed by the doors, fingers were not injured at all.

EXAMPLES 22 AND 23

The production procedure of Example 21 was repeated except that therubber compositions of Examples 8 and 9 were used as the rubbercomposition for the core body to fabricate two different car door seals.These seals were subjected to the door operation test. Neither of theseals was damaged in any manner.

EXAMPLE 24

The rubber composition of Example 4 was presscured under the sameconditions as Examples 1 to 8 to manufacture a cushion (30 cm.×30 cm.×20mm.) having the configuration shown in FIG. 40.

A panel of 10 testers was instructed to evaluate the seating quality ofthis cushion, using a commercial sponge rubber cushion (50 mm. thick) asa control. All the panelists rated the cushion of the present inventionby far superior to the commercial product in seating quality.

EXAMPLES 25 TO 26

The production procedure of Example 24 was repeated except that therubber compositions of Examples 11 and 13 were respectively employed tofabricate two different cushions. Both cushions proved to have excellentseating qualities.

EXAMPLE 27

Using the rubber compositions of Examples 3 and 6, a cushion (30 cm.×30cm.×20 mm.) having the three-layer construction of FIG. 41 wasfabricated. Thus, the rubber composition of Example 6 was used toprepare an uncured rubber sheet for the core layer 82 which was thensandwitched by uncured rubber sheets made of the rubber composition ofExample 3 for the upper and lower layers 83 and 84. The laminate thusobtained was presscured under the same conditions as in Examples 1 to 8.The thickness of the core layer 82 was 10 mm. and that of the upper andlower layers 83 and 84 was 5 mm.

The resultant cushion proved to be more excellent than the cushion ofExample 24 in seating quality.

EXAMPLE 28

The production procedure of Example 27 was repeated except that therubber composition of Example 14 was used as the rubber composition forthe core layer 82 to manufacture a cushion. This cusion was as good asthe product of Example 27 in seating quality.

EXAMPLE 29

The rubber composition of Example 4 was presscured under the sameconditions as in Example 1 to 8 to fabricate a vibration insulatorhaving the configuration shown in FIGS. 1 to 5. The outline of theconfiguration is as follows:

Diameter of body 1: 50 mm.

Height of body 1: 3 mm.

Height of projections 4: 0.5 mm.

Depth of groove 6: 1.0 mm.

Using this insulator in place of each of the rubber vibration insulatorsof a commercial record player, a record listening test was carried out.High fidelity reproduction was obtained with a sufficient suppression ofsound quality deteriorations due to howling and outside vibrations.

EXAMPLE 30

Using the rubber composition of Example 1, a vibration insulator havingthe configuration shown in FIGS. 9 and 10 was manufactured in the samemanner as in Example 29. The outline of the configuration is as follows:

Diameter of body 1: 50 mm.

Height of body 1: 50 mm.

Height of projections 4: .5 mm.

Depth of concavity 6a: 10 mm.

Using the above insulator in place of each of the rubber vibrationinsulators of a commercial record player, a record listening test wascarried out. High fidelity reproduction was obtained with a sufficientsuppression of sound quality deteriorations due to howling and outsidevibrations.

EXAMPLE 31

The rubber composition of Example 4 was press-cured under the sameconditions as in Examples 1 to 8 to manufacture a vibration insulatorhaving the configuration shown in FIGS. 16 to 21. The outline of theconfiguration is as follows:

Vibration-proof member 21

Diameter: 50 mm.

Height: 45 mm.

Height of projections 4: 0.5 mm.

Height of projections 23: 0.5 mm.

Vibration-proof member 22

Diameter of protrusion 22a: 29 mm.

Using the above insulator in place of the rubber vibration insulators ofa commercial record player, a record listening test was carried out.High fidelity reproduction was obtained with a sufficient suppression ofsound quality deteriorations due to howling and outside vibrations.

EXAMPLE 32

The production procedure of Example 31 was repeated except that thevibration-proof members 21 and 22 were made of the rubber compositionsof Example 5 and Example 3, respectively, to manufacture a vibrationinsulator.

Using the resultant insulator in place of each of the rubber vibrationinsulators of a commercial record player, a record listening test wascarried out. High fidelity reproduction was obtained with a sufficientsuppression of sound quality deteriorations due to howling and outsidevibrations.

EXAMPLE 33

The rubber composition of Example 4 was press-cured under the sameconditions as in Examples 1 to 8 to manufacture a vibration insulatorhaving the configuration shown in FIGS. 23 and 24. The core member 31was made of the rubber composition shown in Table 6. The outline of theconfiguration is as follows:

Core member 31

Diameter: 50 mm.

Height: 18 mm.

Thickness of top plate and peripheral wall: 3 mm.

Vibration-proof member 32

Diameter: 50 mm.

Thickness: 2 mm.

Vibration-proof member 33

Maximum diameter: 56 mm.

Maximum height: 15 mm.

Height of projections 4: 0.5 mm.

Using the above insulator in place of each of the rubber vibrationinsulators of a commercial record player, a record listening test wascarried out. High fidelity reproduction was obtained with a sufficientsuppression of sound quality deteriorations due to howling and externalvibrations.

EXAMPLE 34

The rubber compositions of Example 1 to 8 were respectively press-curedunder the same conditions as in Examples 1 to 8 to prepare deadeningmembers (8 mm. thick) having the disk-shaped configuration of FIG. 27.

Each of these deadening members was laminated onto the reverse side ofan aluminum alloy turntable with an adhesive. The turntable was placedin position on a record player and a record performance test was carriedout. The turntable started revolving smoothly without vibrations andsquealing and helped reproduce excellent quality sound.

What is claimed is:
 1. A rubber material which is a cured rubber of a rubber comprising (A) 100 parts by weight of a rubber component, (B) 100 to 2,000 parts by weight of a factice, and (C) 200 to 2,000 parts by weight of a softening agent, the cured rubber having a hardness of from a maximum of 30° as measured with an A-type rubber hardness tester to a minimum of 15° as measured with an F-type rubber hardness tester, an impact resilience of not less than 50% and a tensile strength of 0.1 to 100 kg/cm².
 2. The rubber material of claim 1, wherein the hardness is not more than 20° as measured with the A-type rubber hardness tester.
 3. The rubber material of claim 2, wherein the hardness is not more than 10° as measured with the A-type rubber hardness tester.
 4. The rubber material of any of claims 1, 2 or 3, wherein the impact resilience is not less than 60%.
 5. The rubber material of claim 4, wherein the impact resilience is not less than 70%.
 6. The rubber material of claim 1, wherein the component (A) is polynorbornene.
 7. The rubber material of claim 1, wherein (A) is a rubber component mainly composed of at least one member selected from the group consisting of natural rubber, isoprene rubber, chloroprene rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, nitrile rubber, acrylic rubber, urethane rubber, chlorinated polyethylene, chlorosulfonated polyethylene, epichlorohydrin rubber, polysulfide rubber and silicone rubber.
 8. A vibration-proof member which comprises a cured rubber material comprising (A) 100 parts by weight of a rubber component, (B) 100 to 2,000 parts by weight of a factice and (C) 200 to 2,000 parts by weight of a softening agent, the cured rubber having a hardness of from a maximum of 30° as measured with an A-type rubber hardness tester to a minimum of 15° as measured with an F-type rubber hardness tester, an impact resilience of not less than 50% and a tensile strength of 0.1 to 100 kg/cm².
 9. The vibration-proof member of claim 7, wherein at least one of a plurality of faces which are to come into contact with other members is provided with a large number of projections.
 10. A sound-proof member which comprises a cured rubber material comprising (A) 100 parts by weight of a rubber component, (B) 100 to 2,000 parts by weight of a factice and (C) 200 to 2,000 parts by weight of a softening agent, the cured rubber having a hardness of from a maximum of 30° as measured with an A-type rubber hardness tester to a minimum of 15° as measured with an F-type rubber hardness tester, an impact resilience of not less than 50% and a tensile strength of 0.1 to 100 kg/cm².
 11. A shock-absorbing member which comprises a cured rubber material comprising (A) 100 parts by weight of a rubber component, (B) 100 to 2,000 parts by weight of a factice and (C) 200 to 2,000 parts by weight of a softening agent, the cured rubber having a hardness of from a maximum of 30° as measured with an A-type rubber hardness tester to a minimum of 15° as measured with an F-type rubber hardness tester, an impact resilience of not less than 50% and a tensile strength of 0.1 to 100 kg/cm².
 12. The shock-absorbing member of claim 10, which is a bumper.
 13. A sealing member which comprises a cured rubber material comprising (A) 100 parts by weight of a rubber component, (B) 100 to 2,000 parts by weight of a factice and (C) 200 to 2,000 parts by weight of a softening agent, the cured rubber having a hardness of from a maximum of 30° as measured with an A-type rubber hardness tester to a minimum of 15° as measured with an F-type rubber hardness tester, an impact resilience of not less than 50% and a tensile strength of 0.1 to 100 kg/cm².
 14. A cushioning member which comprises a cured rubber material comprising (A) 100 parts by weight of a rubber components, (B) 100 to 2,000 parts by weight of a factice and (C) 200 to 2,000 parts by weight of a softening agent, the cured rubber having a hardness of from a maximum of 30° as measured with an A-type rubber hardness tester to a minimum of 15° as measured with an F-type rubber hardness tester, an impact resilience of not less than 50% and a tensile strength of 0.1 to 100 kg/cm². 